<h4>Tool</h4><table border="0"><tr><td valign="top"><b>Name</b></td><td valign="top">Flow Accumulation (Recursive)</td></tr><tr><td valign="top"><b>ID</b></td><td valign="top">1</td></tr><tr><td valign="top"><b>Author</b></td><td valign="top">O.Conrad (c) 2001</td></tr><tr><td valign="top"><b>Specification</b></td><td valign="top">grid</td></tr></table><hr><h4>Description</h4>Recursive upward processing of cells for calculation of flow accumulation and related parameters. This set of algorithms processes recursively all upwards connected cells until each cell of the DEM has been processed.

References:

Deterministic 8
- O'Callaghan, J.F. / Mark, D.M. (1984):
    'The extraction of drainage networks from digital elevation data',
    Computer Vision, Graphics and Image Processing, 28:323-344

Rho 8:
- Fairfield, J. / Leymarie, P. (1991):
    'Drainage networks from grid digital elevation models',
    Water Resources Research, 27:709-717

Deterministic Infinity:
- Tarboton, D.G. (1997):
    'A new method for the determination of flow directions and upslope areas in grid digital elevation models',
    Water Resources Research, Vol.33, No.2, p.309-319

Multiple m_Flow Direction:
- Freeman, G.T. (1991):
    'Calculating catchment area with divergent flow based on a regular grid',
    Computers and Geosciences, 17:413-22

- Quinn, P.F. / Beven, K.J. / Chevallier, P. / Planchon, O. (1991):
    'The prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models',
    Hydrological Processes, 5:59-79

<hr><h4>Parameters</h4><table border="1" width="100%" valign="top" cellpadding="5" rules="all"><tr><th>Name</th><th>Type</th><th>Identifier</th><th>Description</th><th>Constraints</th></tr>
<tr><th colspan="5">Input</th></tr><tr><td>Elevation </td><td>Grid (input)</td><td>ELEVATION</td><td></td><td></td></tr><tr><td>Sink Routes (*)</td><td>Grid (optional input)</td><td>SINKROUTE</td><td></td><td></td></tr><tr><td>Weights (*)</td><td>Grid (optional input)</td><td>WEIGHTS</td><td></td><td></td></tr><tr><td>Input for Mean over Catchment (*)</td><td>Grid (optional input)</td><td>VAL_INPUT</td><td></td><td></td></tr><tr><td>Material for Accumulation (*)</td><td>Grid (optional input)</td><td>ACCU_MATERIAL</td><td></td><td></td></tr><tr><td>Accumulation Target </td><td>Grid (input)</td><td>ACCU_TARGET</td><td></td><td></td></tr><tr><td>Target Areas (*)</td><td>Grid (optional input)</td><td>TARGETS</td><td></td><td></td></tr><tr><th colspan="5">Output</th></tr><tr><td>Flow Accumulation</td><td>Grid (output)</td><td>FLOW</td><td></td><td></td></tr><tr><td>Mean over Catchment</td><td>Grid (output)</td><td>VAL_MEAN</td><td></td><td></td></tr><tr><td>Accumulated Material (*)</td><td>Grid (optional output)</td><td>ACCU_TOTAL</td><td></td><td></td></tr><tr><td>Accumulated Material (Left Side) (*)</td><td>Grid (optional output)</td><td>ACCU_LEFT</td><td></td><td></td></tr><tr><td>Accumulated Material (Right Side) (*)</td><td>Grid (optional output)</td><td>ACCU_RIGHT</td><td></td><td></td></tr><tr><td>Flow Path Length (*)</td><td>Grid (optional output)</td><td>FLOW_LENGTH</td><td>average distance that a cell's accumulated flow travelled</td><td></td></tr><tr><td>Loss through Negative Weights (*)</td><td>Grid (optional output)</td><td>WEIGHT_LOSS</td><td>when using weights without support for negative flow: output of the absolute amount of negative flow that occurred</td><td></td></tr><tr><th colspan="5">Options</th></tr><tr><td>Step</td><td>Integer</td><td>STEP</td><td></td><td>Minimum: 1
Default: 1</td></tr><tr><td>Flow Accumulation Unit</td><td>Choice</td><td>FLOW_UNIT</td><td></td><td>Available Choices:
[0] number of cells
[1] cell area
Default: 1</td></tr><tr><td>Method</td><td>Choice</td><td>METHOD</td><td></td><td>Available Choices:
[0] Deterministic 8
[1] Rho 8
[2] Deterministic Infinity
[3] Multiple m_Flow Direction
Default: 3</td></tr><tr><td>Convergence</td><td>Floating point</td><td>CONVERGENCE</td><td>Convergence factor for Multiple m_Flow Direction Algorithm (Freeman 1991)</td><td>Default: 1.100000</td></tr><tr><td>Prevent Negative Flow Accumulation</td><td>Boolean</td><td>NO_NEGATIVES</td><td>when using weights: do not transport negative flow, set it to zero instead; useful e.g. when accumulating measures of water balance.</td><td>Default: 1</td></tr></table>(*) <i>optional</i>